how is it discrimination for the government to tell people of ALL races you can't discriminate against people by virtue of their race?
Let's take this little piece of your question: for the government to tell people ...
You're forgetting that in this country the people tell the government what to do, not the other way around.
Suppose a man wants to discriminate? The government says he can't. That's de facto discrimination.
Now, you may say that's bad, but the deeper question is whether the government can tell a person that he has to run his business in accordance with politically correct social policy?
Put race aside for a moment and see where this leads. Suppose a devout christian owns a coffee shoppe and doesn't want homosexuals hanging out there. Does he have a right to discriminate? It's his business after all. Not according to the government he doesn't.
How about a woman who owns a dress shoppe and desn't want to hire transvestites to work there? Nope. Government says she has to hire them.
We could go on and on with examples of people who want to discriminate but can't. Racial discrimination is only a part of it, but it's the part that started it all.